Ventilation devices serve to carry off the air supplied to the vehicle interior via a ventilation system. The ventilation device includes a frame having a non-return flap mounted therein which can open in case of an overpressure in the vehicle interior, so that air can escape from the vehicle interior. When no air flows out of the vehicle interior, the non-return flap rests against the frame, as a result of which the frame is sealed and an ingress of moisture, dirt or exhaust gases into the vehicle interior is prevented.
A ventilation device of the type initially mentioned is disclosed in DE 20 2006 020 365. Pins which each have a head are used as holding members. The non-return flap is mounted on the holding members by pressing the head of the respective holding member through the recess (“buttonhole”) of the non-return flap in the nature of a button. It has turned out, however, that in operation, the non-return flap can become detached from the holding members, so that a proper functioning is no longer ensured.